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                               9                        Notes
                      DEFORESTATION
         In the previous lessons you have learnt about environment, its components and various
         ecological concepts. You have also acquainted yourself with natural ecosystem and man-
         made ecosystems. Humans have altered the ecosystems according to their own needs
         without thinking about the consequences. Their need combined with greed have caused
         much damage to the environment, which will affect the coming generations. The expansion
         of agriculture, urbanization and industrialization needed the land which was obtained by
         large scale clearing of forests. The deforestation has changed the scenario of developed
         and developing countries, and has brought out vast changes resulting into a various
         environmental problems. In this lesson you are going to study about deforestation, its
         causes and effect on environment.
              OBJECTIVES
         After completing this lesson, you will be able to:
         · define forest and describe the shrinking of forest cover throughout the world;
         · explain the various causes of deforestation;
         · give examples of exploitation of forest resources;
         · define biodiversity, give reasons for its rapid decline, express concern about the
           consequences of biodiversity loss;
         · relate the fast depletion of wildlife and explain the concept of endangered,
           threatened and exotic species and other forest resources due to deforestation;
         · describe how deforestation is contributing towards soil erosion, flash floods and
           change in climate;
         · describe the impact of deforestation on tribal communities;
         · define desert and explain the causes of desertification; and give examples of
           desertification in India;
         · identify the consequences of desertification.
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                            9.1 FORESTS
                           Forests are ecological as well as a socio-economic resource. Forests have to be managed
                           judiciously not only because they are source of various products and industrial raw materials
                   Notes   but also for environmental protection and various services they provide.
                                           rd
                           Approximately 1/3  of the earth’s total land area is covered by forests. The forests provide
                           habitat for wildlife, resources such as timber, fire wood, drugs etc. and aesthetic environment.
                           Indirectly, the forests benefit people by protecting watersheds from soil erosion, keeping
                           rivers and reservoirs free of silt, and facilitate the recharging of groundwater. Forest plays
                           an important role in the cycling of carbon, water, nitrogen and other elements.
                           What is forest? Forest is a complex ecosystem consisting mainly of trees that
                           support a myriad forms of life. The trees are the most important component that help to
                           create a unique environment which, in turn, supports various kinds of animals and plants.
                           Trees are the prime producers for the forest, purify and cool the air and control the climate.
                           Forests may be subdivided into natural forests and plantations or man made forests. Natural
                           forests are forests composed of mainly naturally grown indigenous (local) trees while
                           plantations are forests established by growing trees by humans.
                           Climate, soil type, topography, and elevation are the main factors that determine the type
                           of forest. Forests are classified according to their nature and composition, the type of
                           climate in which they thrive, and its relationship with the surrounding environment. India
                           has a many types of forests: They range from rain forest of Kerala and North-East to
                           deciduous forests in the plains, mountain forests to alpine pastures of Ladakh and deserts
                           of Rajasthan.
                           9.1.1 Types of Forests
                           You have already studied the details of the major types of forests in India in
                           lesson- 6.(Recall Fig.6.2 of lesson-6)
                           9.1.2 Importance of Forests
                           Early life of humans on this planet began as forest dweller. In early days human were totally
                           dependent on forest for food, clothing, and shelter. Even after agriculture was started
                           humans remained dependent upon the forests for several of their needs. The source of fuel
                           wood and provide raw materials to various wood industries. Indian forests also provide
                           many other valuable minor products such as essential oil, medicinal plants, resins, turpentine
                           etc. Forests are renewable resources which provide a wide variety of commodities. Forests
                           satisfying aesthetic needs of humans and have been a source of inspiration for the
                           development of culture and civilization. Forests are home to a very large variety of plants,
                           animals and micro-organisms. This great richness of flora and fauna which has evolved
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                   Deforestation                                                                                     MODULE - 3
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                  over the years is an important part of nature. Forests provide habitat and food as well as
                  protection to wildlife species against extremes of climate.
                  Forests have great biological importance as reservoirs of genetic diversity apart from
                  playing an important role in regulating earth’s climate.                                         Notes
                  Forest carry out many important vital functions given in the following tables.
                                          Table 9.1: Main functions of the forests
                             Functions                                      Benefits 
                    Productive functions            Production of various types of wood, fruits and a wide 
                                                    range of compounds such as resins, alkaloids, essential 
                                                    oil, latex and pharmaceutical substances. 
                    Protective functions            Provides habitats for various organisms conservation of 
                                                    soil  and  water,  prevention  of  drought,  shelter  against 
                                                    wind, cold, radiation, noise, sounds, smells and sights. 
                    Regulative functions            Absorption,  storage  and  release  of  gases  (most 
                                                    importantly  carbon  dioxide  and  oxygen),  water, 
                                                    minerals,  elements  and  radiant  energy.  All  such 
                                                    functions  improve  the  atmospheric  and  temperature 
                                                    conditions    and    enhances     the    economic     and 
                                                    environmental value of the land .Forests also effectively 
                                                    regulate floods and drought and all the biogeochemical 
                                                    cycles. 
                  · Timber
                  India and other tropical countries have particularly abundant timber and heartwood
                  resources. Timber accounts for 25% of all photosynthetic materials produced on the earth
                  and about half of the total biomass produced by a forest. A large number of trees are
                  commercially exploited for timber in different parts of India. Timber-based industries include
                  plywood manufacture, saw milling, paper and pulp, composite wood, matches, man-made
                  fibres, furniture, sports goods, and particle boards.
                  · Medicinal plants
                  About 40% of all the drugs used throughout the world have active ingredients extracted
                  from plants and animals. Drugs which are derived from natural compounds amount to at
                  least $40 billion worldwide sales annually. For example quinine is used to treat malaria
                  (from the cinchona tree); Digitalis is used to treat chronic heart trouble (from the foxglove
                  plant, Cinchona officinalis); and morphine and cocaine are used to reduce pain;drug for
                  leukemia from Vinca rosea, taxol from Taxus brevifolia etc; and hundreds of life saving
                  antibiotics. In recent years more than 5000 species of flowering plants have been analysed
                  by scientists for the presence of valuable drugs.
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                                     Asprin, which is probably the world’s most widely used drug was developed
                                     according to a chemical “blueprint”, from a compound extracted from the leaves of
                                     tropical willow trees.
                       Notes
                                          INTEXT QUESTIONS 9.1
                                 1.   Make the list of plants used for medicinal purposes along with the botanical names
                                      and the disease for which they are used.
                                      ______________________________________________________________
                                 2.   What are the main functions of forests?
                                      ______________________________________________________________
                                 3.   List various timber based industries.
                                      ______________________________________________________________
                                  9.2 DEFORESTATION
                                 Deforestation is a very broad term, which consists of cutting of trees including repeated
                                 lopping, felling, and removal of forest litter, browsing, grazing and trampling of seedlings. It
                                 can also be defined as the removal or damage of vegetation in a forest to the extent that it
                                 no longer supports its natural flora and fauna.
                                     The rapid rate of deforestation in the tropics is a key driving force in the yearly
                                     increase of flood disasters.
                                 Deforestation refers to the loss of tree cover; land that is permanently converted from
                                 forest to non-forest uses such as agricultural pasture, desert, and human settlement.
                                 In the beginning of 20th century about 7.0 billion hectares of forests were  present over the
                                 land of our planet and by 1950 forest covers was reduced to about 4.8 billon. If the
                                 present trend continues forests will be reduced to only 2.35 billion ha hectares in 2000 A.D.
                                 In a FAQ/UNEP study it was found that about 7.3 million hectares of rich tropical forests
                                 every year and about 14 hectare of closed forest every minute are lost.
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